House electbic



April 17, 1928. 1,666,523

R. W. BAILEY TREATMENT OF STEAM I'd REDUCE 0R PREVENT CORROSION FiledDec. 17, 1921 WITNESSES: INVENTOR ATTORNEY Patented Apr. 17, 1928.

UNITED STATES PATENT OFFICE.

RICHARD WILLIAM BAILEY, OF ALTRINCHAM, ENGLAND, ASSIGNOR TO WESTING-HOUSE ELECTRIC.& MANUFACTURING COMPANY, A. CORPORATION OF PENNSYL-VANIA.

TREATMENT OF STEAM TO REDUCE OR PREVENT CORROSION. I

Application filed December 17, 1921, Serial No. 523,054, and in GreatBritain December 20, 1820.

This invention relates to means for reducing or preventing corrosion ofturbine blad ing. It has been observed that the corrosion of the bladingof steam turbines appears to be most severe in the region where moisture is first formed and where the moisture content or wetness of thesteam is comparatively low. The moisture content of the steam increasesas it passes through the turbine towards the condenser and this isaccompanied by a diminution of corrosion until in the last stages ofexpansion of the.

steam it is often negligible. The comparatively high rate of corrosionwhere moisture is first formed and where the'moisture content is low isthought to be due to the fact that the water particles dissolve theactive gases in the steam thereby rendering them corrosive and carrythem at an appreciable degree of concentration to the blade su1-- faces.At a later stage in the expansion of the steam the increasing'quantityof water present together with the partial exhaustion or neutralizationof the corrosive elements which has taken place and the reductionintemperature results in diminishing the corrosion to an amount which isnot serious.

In the accompanying drawing, I show a schematic representation of aturbine embodying my device.

According to the present invention, in order to reduce or preventcorrosion of turbine blading, liquid in the form of a fine spray oratomized condition is injected into the steam which operates theturbine. The liquid employed may either be Water. or an alkali whichwill dilute or neutralize the action of corrosive constituents, such asfree oxygen or both water and a neutralizing solution may be separatelyinjected in the steam path.

In the accompanying drawing, I show a. somewhat diagrammatic "elevationof a steam power installation, comprising a water tube boiler 10,- whichis provided with a superheater 11, from which steam is supplied throughthe throttle valve I2,'to an elastic fluid turbine 13, in a manner wellunderstood in the art. I

In expanding through the turbine, the steam gradually loses itssuperheat and becomes wet steam, the zone in which the change fromsuperheated to wet steam takes place being indicated by b, while thezones of superheated and of wet steam are indicated by a andrespectively.

In order to reduce the corrosive action of the steam in this zone ofchange, I provide suitable nozzles 14, which are arranged to be suppliedwith a suitable inert liquid diluent from the manifold 16. hile I haveshown a plurality of nozzles, it will be understood that only one may beused, and also that the nozzles need not be all disposed to dischargeinto the same stage as shown. Preferably, the nozzles are arranged todischarge into a stage of the turbine on the high pressure side of thezone of change 1) as shown.

In the case where water only is employed, the injection may take placeeither at that part of the steam path where moisture is first formed ora little earlier in the super-' heated region. From thermodynamicconsiderations the temperature of the' water should be equal or asnearly equal as pos sible to the saturation temperature corresponding tothe temperature of the steam at the point of injection and the rate ofinjection should be proportionate to the flow of steam to, in effect,give a degree of dilution which prevents or adequately reducescorroslon.

Where an alkali is employed, this isinjected at a stage of the turbinein which the steam is still superheate'd,the object'being to providealkali or other nuclei around which moisture can form and thereby theactive corrosive substances may be diluted to such an extent thatcorrosion is reduced due to the dissolution of the corrosive substancesby the water particles. Preferably a solution is used whose boilingpoint is higher than that of water under the same condition of pressureand consequently the liquid can exist as such at the point of injectionand be available for performing the function above mentioned.

An aqueous solution of caustic soda. is a suitable'medium to employ whenblades of ferrous material are used in the turbine, but the invention isnot limited to the use of this substance as the most suitable substancewould be determined by a consideration of the corrosive constituents ofthe steam having regard to the material of the blades and the action onother parts of the plant, the condenser tubes, for example. Other solu-.

tions suitable to employ are solutions of the carbonates and hydroxidesof sodium and potassium, also any other soluble hydroxides.

Where the liquid is to be injected into the steam path where the steamis superheated,

y it may obviously be injected on either side of a suitable nozzle ornozzles to which the liquid is supplied at a suitable pressure, saidnozzles being adapted to atomize the liquid into the form of a finespray. In some cases it may be desirable to provide a number of suchnozzles so that the injection liquid may be distributed throughout thebody of the steam passing throughthe turbine at the stage or stageswhere the injection takes place. 7

While I have disclosed a plurality of ways in which my invention may bepracticed, it will be obvious to those skilled in the art that it is notso limited, but is susceptible of being used or applied in various otherways without departing from the spirit thereof, and-I desire, therefore,that only such limitations shall be placed thereupon as are imposed bythe prlor-art or as are specifically set forth in the appended claims.What I claim is Q 1. The process of minimizing corrosion in machines forabstractin the available energy of steam in the production of mechanicalpower, and in which steam changes from a superheated to a saturatedcondition, which consists in injecting an inert liquid diluent into thesteam on the high pressure do of the zone of change from superheated tosaturated conditions.

2. The process of reducing corrosion machines for abstracting theavailable energy of steam in the production of mechanical power, and inwhlch steam changes from a superheated 'to a saturated condition, whichconsists in injecting an inert liquid diluent, at a temperaturesubstantially corresponding to the saturation temperature of the steamin the zone of change from superheated to saturated conditions, into thesteam entering the zone of change.

3. The process of reducing corrosion in machines for abstracting theavailable energy of steam in the roduction of mechanical power, and inwhich steam changes from superheated to wet steam, which consists in inecting an inert liquid diluent, at a rate proportionate to the flow ofsteam, into the steam on the high pressure side of the zone of changefrom su erheated to wet steam.

In testimony w ereof, I have hereunto subscribed my name this 24th dayof November, 1921.

' RICHARD WILLIAM BAILEY.

